Vacuum tube amplifier system



Sept. 19, 1933. P, E. EDELMAN 1,927,628

VACUUM TUBE AMPLIFIER SYSTEM Filed Feb. 20, 1928 \n 3 i g 3 HIIIIIIIII/IIIIIIIIIIIIIIII'J Patented Sept. 19, 1933 g v Q i i UNITED s*rA'r1-:.-s PATENT FICE,

VACUUM TUBE AMPLIFIER SYSTEM Philip E. Edelman, Chicago, Ill., assignor, by mesne assignments, to Robert 'T. Mack, trustee, Chicago, Ill.

Application February 20, 1928. Serial No. 255,814

' 1 Claim. (01. 179171) Good amplification via a sequence of vacuum be desired. When socket 8 is used, wires 7, 6, contubes requires that the input energy be amplified nected to line 4, 5, one of'which is groundedat without. undesired amplification of side noises 3, serve to conduct carrier frequency energy inrepresented in the input energy and the partially tercepted thereby, to plug9. A switch 13 permits amplified energy. This invention has for its switch arm 14 to connect with either conductor 11 60 object to increase the fidelity of responsive amplior 12 from plug 9. High frequency, energy can fication to the desired portion of the input energy pass from switch arm 14 through the wire 10, while excluding the undesired portion thereof fuse l5, fixed condenser'lS and tuning condenser from the amplified output, and is a continuation 17 thru coils 18 and 19 and thence via wire' 25' I in part of my original application S. No. 566,132, to ground '36. Radiofrequency energy passing 65 filed in the United States Patent Office June 5, thru coils 18 and 19 will induce similar energy in 1922, which became Patent No. 1,665,897. coils 24 and 23 coupled thereto as controlled: at The elements of an amplifier system are wel conducting terminals 20, 39 by variable condenser known in the prior art but I have conceived that 21. A by-pass' condenser 2'7 connects through the improved results may be had by a new and useful wire 28 to coil 19 and also connects to coil 24 and 7 combination of the parts. I illustrate by way conducting plate 31. A selector or filter coil 22 of example a suitable embodiment of my invenconnects to condenser 21 and coil 23 and can tion in the accompanying drawing which is a feed energy to grid input wire 26 of vacuum tube schematic diagram showing the invention ap- 99. Partially selected energy obtainedthrough 20, plied to a sequence of vacuum tubes. the plug 9 can thus be used to'control thefinput 7 An amplifier of the class described includes: to the first vacuum tube 99, though some energy means to select input energy; usually at high other than desired and selected may force itself frequency, a convertor or detector stage to thru filter coil 22. change energy amplified therefrom to lower fre- Each. vacuum tube. 99, 96, 56 and 53 hasthe '25 quency bands, and a further amplifier for the customary three elements, filament, grid and plate 0 last named energy. respectively, and a fourth control element 58.

Heretofore selection between desired and un- All of the control resistances58 connect tocomdesired input energy has been sought by selective mon plate conductor 31 at. '55, 60, andv 54, re-

tuning means introduced in or ahead of the input spectively. Conductorv plate 31 connects through 30, to the amplifier and tuned to a particular highthe wire 37 to filament power supply fil and switch 85.

frequency band. It is known that all such selectcontrols the current fed therefrom through the ing means or filters absorb'and dissipate conwire 34, resistance 33, rheostatarm 32, {wire 30' siderable energy so that the degree of selection and the wires 29, 100, 101, and respectively.

or pre-filtering prior to amplification is very A plate power supply source 38 connects via wire 35. limited when the-input energy is feeble. 'From 40 to wire 37 and thence to conductor plate 31,

considerations, showing that an effective filter can and suitable potential taps therefrom are probe had to handle larger amounts of energy where vided at 42, 4 3 and 44 :to' feed current via wires the filter or selector losses are insufilcient to bar 57 and 45 respectively. i efficient transfer of amplified energy, I prefer Platecurrent for vacuum tube 99 is fed through to arrangeonly a partial selector ahead of the the wire5'7, resistance 8'7, wire 86, wire 90, switch amplifier input,'permitting both desired andunarm 91 and tapped coil 92 and its terminal wire desired energy to be amplified up to a certain 98. Aby-pass condenser 95 connects through the stage, and then to introduce a power type filter wire 93 to switch arm 91, and through the wire or selector to further selectively amplify the 97 to conductor plate 31. Radio frequency energy 45 aforesaid amplified output. In this manner, selected from plug connector 9 and partially fil- 100 feeble input energy can be effectively amplified tered by coil 22 maythus be converted and amwith suppression of undesired noises from the plified by vacuum tube 99 with appropriate adlast amplifier stage output. Various changes and justment of coil 92, so that the amplified radio modifications may be made without departing frequency energy from vacuum tube .99 will 50 from the idea of the invention and within the mainly flow thru condenser 95 while the 0011- scope of the appended claim. verted frequency component of the amplified out- Referring to the drawing, input energy for the put thereof can flow to conductor plate 31 through amplifier can be selected from either the aerial the wire 90, wire 86,resistance'8'7, wire 57,'power 5 1 or the power line 4, 5 by means of attachment supply 38 and wires 40, 3'7. In so flowing thru plug 9 which fits in either socket 8 or 2 as may resistance 8'7 at lower converted band of fre- 11.

vacuum tube 56.

quencies controlledby'vacuum tube SQ Simiia-r potentials will be set up at wire'89 connected to wire 90 and can pass-to grid input wire 940i vacuum tube 96 via controlling condenser 88. A 1 shunt resistance 85 connects to input'wire 94 and also connects to conductor plate 31 through the wire 84 The input 94 to vacuum tube 96 is thus responsive'toall the bands of frequencies conresistance 83 to wire 104 and thence'to conductor plate Vacuum tube 56receives plate current supply from power source 38 via switch 43, wire" t5, wire fifi, resistance 70, wire 82 and wire 1,03. The amplified currents passing thru resistance 70 f are able to apply potential to condenser 69' which 53. A shunt'resistance 68 to conductor plate 31,

connects with grid input wire 67 of vacuum tube also connects wire 67 A filter circuit comprised by condenser 72, and condenser 71,-with condenser 71 shuntedby imfpeda'n'ce' coils 76 and 75, also interconnects wire 103 of vacuum tube 56,to' resistance68 and 70. Coil .75 connectsthroughthe wire 74 to one ter minal 78 ofcondenser 71 while-coil 76 connects (to the other terminal 77 thereof and to one ter minal of condenser 72. Most of the energy pass ing to wire 67 of vacuum tube 53 must pass thru this filter section: between vacuum tube 56 and vacuum tube53 and energy at frequenciesbarrcd by filter coils 76 and'75, with condensers 71f'and 7 2, can only'affect grid input wire 67 in minute amount. compared with the desiredcne'rgy input [fed thereto, therebyr An efiec'tive input power filter for vacuum, tube 53 isthus provide'dpat a stage where the filter losses are small on the energy to be amplifiedyso thatvacuum tube 53 serves substantially only as'an amplifier" for the desired pre-amplified and'filtere'd energy made available by. vacuum tube 56 .and the aforesaid circuits connected thereto., Vacuum'tube 53 can thus supplyoutput energy through the wire 54.,

wire 52, battery 51-, .wire16l, reproducer 49 with its horn 48, wire 46*conn'ecting'at'junction l7 to wire 45, andfthence-to plate current supplyjfia,

Thus; the'.'undes'ired: energy which is amplified through thefvacuum tubes 99, 96 and56 in order to simultaneously build upa large value .pf am- "plified energy which is desired, -is selectivelyfil- *,teredat the stage where filter losses on the cle sired energy input are unimport'ant owing to the c amplifiedvaluethereof, permittingpower filter 76, 75,71 72 to efficiently select the input sup plied to grid'connection 67 of amplifierfvacuum tube 53. UndesiredTenergy forced thru @1122 and] amplified in vacuum'tubes 99, 96 and is thus so greatly diminished at the input wire '67 t r with respect to the desired energy, simultaneously applied at wire 67, that the 'output wire 640i vacuum tube 53 carries substantially no ene rgy amplified at the ir'equencies barred by said, power filter 76, 71and 72. This arrangement thus provides effective amplification-ofthe desired energy and permits the'values of coils 76, 75, cont l densers 71 and .72 alsoresistances 63 and70 and condenser'69 to'beselected to suppress and dissipate amplified values of predetermined frequency bands, while passing energy of desired pre-sele'cte'd frequencyband.

' It will "be observed that conductor plate 7 31 1 1 serves as' an equal potential junction between the t Y vacuum'tubes 99, 96;5 6, and 53, not grounded.

except through the condenser 27. There is thus shown a suitable embodiment illustrating the practiceof the invention whereby input energy to thefirst of a series of vacuum tubes is partially selected and amplified along with undesired energy in order not. to lose too, much of the desired energy;' then afterthe desired energy has been: subsequently amplified to a large ,amplitudefa, i

power filter or band; Salaam-enemas usdfin the input to the lastpvacuumitube of'the series in'order'to substantially ba'r final amplification of any but the desired energy represented in. the

selected band. It} may be remarked-that this arrangement produces] surprising results and makes effective use iof the characteristics of each vacuum' tube 99, 96, 56 respectively, which are able to'amplify the energy input thereto respec-i tively only to the ability-of each said tube, thus permitting the weaker desired energy represented in the finally selectedbandosf frequencies to overtake, so tospeak, the undesired bands and :be

forth in the "final amplifier input t'orvacuum tube 53.

The constants 'of, the circuits Will be designed vin accordance with the bandsto' be barred and selected as is customary in "theart and suitable formula therefor may be found in U. S. Patent, N0. 1127,113, also 1,127,11f1 The invention is applicable to'a'radio receiving system, or the pointed out in the like, and is more particularly apphdedclaim. t V n Iclaim; Q In an amplifier'system'of the classdescribed,

.means to couple two; vacuum, tube amplifier 'stages each having plate and grid circuits com-.

effectively selected finally bythe power filterset prising a band filternetwork composedi'ot 'a'first resistancein theplate circuitotthe first vacuum tubej'a second resistance 'in the grid circuit of the second vacuum I tubefa condenser joining said first resistance to the grid of 'said second vacuum tube, two condensers in series wc c'mnecting the plate of said first vacuum tube to'said second resistance, an inductance shuntedtaround one of? said last named two series condensers; means to feedoperating plate current] through said first resistance; and means to conduct operating grid potential throughsaid second resistance.

.ePHILIP EIEDELMANI, f a 

